1. Field of the Invention
This invention relates generally to an aperture structure in a heat insulation box or container and, more particularly, to such an improved and simple aperture structure which can not only facilitate fabrication and assembly of the heat insulation container, but also prevent leakage of a heat insulating material through the aperture structure when the material is charged into and foamed in the casing of the heat insulation container.
2. Prior Art
A heat insulation container is widely used in various refrigerating or cooling apparatuses such as a refrigerator, an ice-making machine, a freezing apparatus, a cold preserving box, a show-case equipped with a cooling system and others. In the refrigerating apparatuses of these types, a compressor, condenser and the like constituting a cooling system are usually disposed exteriorly of the heat insulation container while a cooler or evaporator constituting another part of the abovementioned cooling system is disposed within the heat insulation container. Accordingly, the container has to be provided with an aperture for allowing fluid communication of the compressor, condenser or the like with the cooler or evaporator accommodated therein so that a coolant can be circulated through the evaporator from the compressor.
FIG. 6 of the accompanying drawings shows a typical aperture structure of a heat insulation container known heretofore. Referring to FIG. 6 which shows, in fragmental vertical section, a wall structure defining an aperture or opening, an annular frame 3 formed of stainless steel or the like and having a channel-like cross section is fixedly mounted by means of rivets 4 on a peripheral edge portion of the aperture provided in an inner casing 1 constituting a part of the wall structure of the heat insulation container. An annular gap 5 is provided between the peripheral edge of the opening formed in an outer casing 2 and the frame 3 to block heat transmission therebetween. This gap is closed by an annular sealing film member 6 adhesively bonded to the inner surfaces of the outer casing 2 and the frame 3 for preventing a heat insulating foamed material from leaking through the gap. Additionally, a tape member 7 is adhesively bonded to an inner surface 1a of the inner casing 1 and an inner surface 3A of the frame 3 for hermetically sealing a junction 8 between the frame 3 and the inner casing 1 connected together by the rivets 4 as well as the riveted portions 8a themselves. The interior space defined by the inner casing 1, the outer casing 2 and the frame 3 is filled with the heat insulating foamed material.
In the case of the prior aperture structure described above, the film member 6 and the tape member 7 must be adhered to and annularly along the inner surfaces of the outer casing 2 and the frame 3 on one hand and to the inner surfaces of the inner casing 1 and the frame 3 on the other hand in order to prevent leakage of the heat insulating material which leakage would otherwise occur upon foaming thereof. In conjunction with the bonding or adhesion of the film member 6 and the tape member 7, experience shows that great difficulty is encountered in attaching the film member 6 to the inner surfaces of the outer casing 2 and the frame 2 in the annular form for hermetically closing or sealing the annular gap 5 between the outer casing 2 and the frame 3, involving degraded efficiency in the assembling process, even when the outer casing 2 is mounted after adhesion of the tape member 7 has been carried out following the mounting of the frame 3 to the inner casing 1 by means of the rivets 4 or the like.